Devices, systems, and methods for communicating pattern matching results of a parallel pattern search engine

ABSTRACT

Disclosed are methods and devices, among which is a system that includes a device that includes one or more pattern-recognition processors for searching a data stream. The pattern-recognition cluster may include various search pattern matching matrices and mask modules which may be utilized to perform various searching functions. Additionally, a buffer may be utilized to individually store the various results from pattern matching matrices and mask modules for subsequent retrieval.

BACKGROUND

1. Field of Invention

Embodiments of the invention relate generally to pattern-recognition processors and, more specifically, in certain embodiments, to the communication of resultant data from multiple operations of the pattern-recognition processors.

2. Description of Related Art

In the field of computing, pattern recognition tasks are increasingly challenging. Ever larger volumes of data are transmitted between computers, and the number of patterns that users wish to identify is increasing. For example, spam and malware are often detected by searching for patterns in a data stream, e.g., particular phrases or pieces of code. The number of patterns increases with the variety of spam and malware, as new patterns may be implemented to search for new variants. Searching a data stream for each of these patterns can form a computing bottleneck. Often, as the data stream is received, it is searched for each pattern, one at a time. The delay before the system is ready to search the next portion of the data stream increases with the number of patterns. Thus, pattern recognition may slow the receipt of data.

Pattern recognition tasks are often complicated by the various types of matches that are to be performed. Certain data streams may match several patterns in short succession, and these various matches may be cataloged. Retrieval of these matches may slow the overall performance of the system, thus causing the system to fail to respond quickly as new matches are occurring. In other instances, a data stream may be received for a relatively long period of time before a match occurs, leaving capacity of other components to process matches unused. The irregular flow of results data during pattern recognition makes it difficult to design systems that interface with pattern-recognition hardware.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 depicts an example of system that searches a data stream;

FIG. 2 depicts an example of a pattern-recognition processor in the system of FIG. 1;

FIG. 3 depicts an example of a search-term cell in the pattern-recognition processor of FIG. 2;

FIGS. 4 and 5 depict the search-term cell of FIG. 3 searching the data stream for a single character;

FIGS. 6-8 depict a recognition module including several search-term cells searching the data stream for a word;

FIG. 9 depicts the recognition module configured to search the data stream for two words in parallel;

FIGS. 10-12 depict the recognition module searching according to a search criterion that specifies multiple words with the same prefix;

FIG. 13 depicts a second example of a pattern-recognition processor in the system of FIG. 1;

FIG. 14 depicts an example of a results buffer in the pattern-recognition processor of FIG. 13; and

FIG. 15 illustrates a series of register banks utilized in conjunction with the results buffer of FIG. 14.

DETAILED DESCRIPTION

FIG. 1 depicts an example of a system 10 that searches a data stream 12. The system 10 may include a pattern-recognition processor 14 that searches the data stream 12 according to search criteria 16.

Each search criterion may specify one or more target expressions, i.e., patterns. The phrase “target expression” refers to a sequence of data for which the pattern-recognition processor 14 is searching. Examples of target expressions include a sequence of characters that spell a certain word, a sequence of genetic base pairs that specify a gene, a sequence of bits in a picture or video file that form a portion of an image, a sequence of bits in an executable file that form a part of a program, or a sequence of bits in an audio file that form a part of a song or a spoken phrase.

A search criterion may specify more than one target expression. For example, a search criterion may specify all five-letter words beginning with the sequence of letters “cl”, any word beginning with the sequence of letters “cl”, a paragraph that includes the word “cloud” more than three times, etc. The number of possible sets of target expressions is arbitrarily large, e.g., there may be as many target expressions as there are permutations of data that the data stream could present. The search criteria may be expressed in a variety of formats, including as regular expressions, a programming language that concisely specifies sets of target expressions without necessarily listing each target expression.

Each search criterion may be constructed from one or more search terms. Thus, each target expression of a search criterion may include one or more search terms and some target expressions may use common search terms. As used herein, the phrase “search term” refers to a sequence of data that is searched for, during a single search cycle. The sequence of data may include multiple bits of data in a binary format or other formats, e.g., base ten, ASCII, etc. The sequence may encode the data with a single digit or multiple digits, e.g., several binary digits. For example, the pattern-recognition processor 14 may search a text data stream 12 one character at a time, and the search terms may specify a set of single characters, e.g., the letter “a”, either the letters “a” or “e”, or a wildcard search term that specifies a set of all single characters.

Search terms may be smaller or larger than the number of bits that specify a character (or other grapheme—i.e., fundamental unit—of the information expressed by the data stream, e.g., a musical note, a genetic base pair, a base-10 digit, or a sub-pixel). For instance, a search term may be 8 bits and a single character may be 16 bits, in which case two consecutive search terms may specify a single character.

The search criteria 16 may be formatted for the pattern-recognition processor 14 by a compiler 18. Formatting may include deconstructing search terms from the search criteria. For example, if the graphemes expressed by the data stream 12 are larger than the search terms, the compiler may deconstruct the search criterion into multiple search terms to search for a single grapheme. Similarly, if the graphemes expressed by the data stream 12 are smaller than the search terms, the compiler 18 may provide a single search term, with unused bits, for each separate grapheme. The compiler 18 may also format the search criteria 16 to support various regular expressions operators that are not natively supported by the pattern-recognition processor 14.

The pattern-recognition processor 14 may search the data stream 12 by evaluating each new term from the data stream 12. The word “term” here refers to the amount of data that could match a search term. During a search cycle, the pattern-recognition processor 14 may determine whether the currently presented term matches the current search term in the search criterion. If the term matches the search term, the evaluation is “advanced”, i.e., the next term is compared to the next search term in the search criterion. If the term does not match, the next term is compared to the first term in the search criterion, thereby resetting the search.

Each search criterion may be compiled into a different finite state machine in the pattern-recognition processor 14. The finite state machines may run in parallel, searching the data stream 12 according to the search criteria 16. The finite state machines may step through each successive search term in a search criterion as the preceding search term is matched by the data stream 12, or if the search term is unmatched, the finite state machines may begin searching for the first search term of the search criterion.

The pattern-recognition processor 14 may evaluate each new term according to several search criteria, and their respective search terms, at about the same time, e.g., during a single device cycle. The parallel finite state machines may each receive the term from the data stream 12 at about the same time, and each of the parallel finite state machines may determine whether the term advances the parallel finite state machine to the next search term in its search criterion. The parallel finite state machines may evaluate terms according to a relatively large number of search criteria, e.g., more than 100, more than 1000, or more than 10,000. Because they operate in parallel, they may apply the search criteria to a data stream 12 having a relatively high bandwidth, e.g., a data stream 12 of greater than or generally equal to 64 MB per second or 128 MB per second, without slowing the data stream. In some embodiments, the search-cycle duration does not scale with the number of search criteria, so the number of search criteria may have little to no effect on the performance of the pattern-recognition processor 14.

When a search criterion is satisfied (i.e., after advancing to the last search term and matching it), the pattern-recognition processor 14 may report the satisfaction of the criterion to a processing unit, such as a central processing unit (CPU) 20. The central processing unit 20 may control the pattern-recognition processor 14 and other portions of the system 10.

The system 10 may be any of a variety of systems or devices that search a stream of data. For example, the system 10 may be a desktop, laptop, handheld or other type of computer that monitors the data stream 12. The system 10 may also be a network node, such as a router, a server, or a client (e.g., one of the previously-described types of computers). The system 10 may be some other sort of electronic device, such as a copier, a scanner, a printer, a game console, a television, a set-top video distribution or recording system, a cable box, a personal digital media player, a factory automation system, an automotive computer system, or a medical device. (The terms used to describe these various examples of systems, like many of the other terms used herein, may share some referents and, as such, should not be construed narrowly in virtue of the other items listed.)

The data stream 12 may be one or more of a variety of types of data streams that a user or other entity might wish to search. For example, the data stream 12 may be a stream of data received over a network, such as packets received over the Internet or voice or data received over a cellular network. The data stream 12 may be data received from a sensor in communication with the system 10, such as an imaging sensor, a temperature sensor, an accelerometer, or the like, or combinations thereof. The data stream 12 may be received by the system 10 as a serial data stream, in which the data is received in an order that has meaning, such as in a temporally, lexically, or semantically significant order. Or the data stream 12 may be received in parallel or out of order and, then, converted into a serial data stream, e.g., by reordering packets received over the Internet. In some embodiments, the data stream 12 may present terms serially, but the bits expressing each of the terms may be received in parallel. The data stream 12 may be received from a source external to the system 10, or may be formed by interrogating a memory device and forming the data stream 12 from stored data.

Depending on the type of data in the data stream 12, different types of search criteria may be chosen by a designer. For instance, the search criteria 16 may be a virus definition file. Viruses or other malware may be characterized, and aspects of the malware may be used to form search criteria that indicate whether the data stream 12 is likely delivering malware. The resulting search criteria may be stored on a server, and an operator of a client system may subscribe to a service that downloads the search criteria to the system 10. The search criteria 16 may be periodically updated from the server as different types of malware emerge. The search criteria may also be used to specify undesirable content that might be received over a network, for instance unwanted emails (commonly known as spam) or other content that a user finds objectionable.

The data stream 12 may be searched by a third party with an interest in the data being received by the system 10. For example, the data stream 12 may be monitored for text, a sequence of audio, or a sequence of video that occurs in a copyrighted work. The data stream 12 may be monitored for utterances that are relevant to a criminal investigation or civil proceeding or are of interest to an employer.

The search criteria 16 may also include patterns in the data stream 12 for which a translation is available, e.g., in memory addressable by the CPU 20 or the pattern-recognition processor 14. For instance, the search criteria 16 may each specify an English word for which a corresponding Spanish word is stored in memory. In another example, the search criteria 16 may specify encoded versions of the data stream 12, e.g., MP3, MPEG 4, FLAC, Ogg Vorbis, etc., for which a decoded version of the data stream 12 is available, or vice versa.

The pattern recognition processor 14 may be hardware that is integrated with the CPU 20 into a single component (such as a single device) or may be formed as a separate component. For instance, the pattern-recognition processor 14 may be a separate integrated circuit. The pattern-recognition processor 14 may be referred to as a “co-processor” or a “pattern-recognition co-processor”.

FIG. 2 depicts an example of the pattern-recognition processor 14. The pattern-recognition processor 14 may include a recognition module 22 and an aggregation module 24 having an output buffer 51. The output buffer 51 may include a results buffer 25. The recognition module 22 may be configured to compare received terms to search terms, and both the recognition module 22 and the aggregation module 24 may cooperate to determine whether matching a term with a search term satisfies a search criterion. The results buffer 25 may buffer results data from the other portions of the patter-recognition processor 14, as will be described further below with regard to FIG. 13.

The recognition module 22 may include a row decoder 28 and a plurality of feature cells 30. Each feature cell 30 may specify a search term, and groups of feature cells 30 may form a parallel finite state machine that forms a search criterion. Components of the feature cells 30 may form a search-term array 32, a detection array 34, and an activation-routing matrix 36. The search-term array 32 may include a plurality of input conductors 37, each of which may place each of the feature cells 30 in communication with the row decoder 28.

The row decoder 28 may select particular conductors among the plurality of input conductors 37 based on the content of the data stream 12. For example, the row decoder 28 may be a one byte to 256 row decoder that activates one of 256 rows based on the value of a received byte, which may represent one term. A one-byte term of 0000 0000 may correspond to the top row among the plurality of input conductors 37, and a one-byte term of 1111 1111 may correspond to the bottom row among the plurality of input conductors 37. Thus, different input conductors 37 may be selected, depending on which terms are received from the data stream 12. As different terms are received, the row decoder 28 may deactivate the row corresponding to the previous term and activate the row corresponding to the new term.

The detection array 34 may couple to a detection bus 38 that outputs signals indicative of complete or partial satisfaction of search criteria to the aggregation module 24. The activation-routing matrix 36 may selectively activate and deactivate feature cells 30 based on the number of search terms in a search criterion that have been matched.

The aggregation module 24 may include a latch matrix 40, an aggregation-routing matrix 42, a threshold-logic matrix 44, a logical-product matrix 46, a logical-sum matrix 48, and an initialization-routing matrix 50.

The latch matrix 40 may implement portions of certain search criteria. Some search criteria, e.g., some regular expressions, count only the first occurrence of a match or group of matches. The latch matrix 40 may include latches that record whether a match has occurred. The latches may be cleared during initialization, and periodically re-initialized during operation, as search criteria are determined to be satisfied or not further satisfiable—i.e., an earlier search term may need to be matched again before the search criterion could be satisfied.

The aggregation-routing matrix 42 may function similar to the activation-routing matrix 36. The aggregation-routing matrix 42 may receive signals indicative of matches on the detection bus 38 and may route the signals to different group-logic lines 53 connecting to the threshold-logic matrix 44. The aggregation-routing matrix 42 may also route outputs of the initialization-routing matrix 50 to the detection array 34 to reset portions of the detection array 34 when a search criterion is determined to be satisfied or not further satisfiable.

The threshold-logic matrix 44 may include a plurality of counters, e.g., 32-bit counters configured to count up or down. The threshold-logic matrix 44 may be loaded with an initial count, and it may count up or down from the count based on matches signaled by the recognition module. For instance, the threshold-logic matrix 44 may count the number of occurrences of a word in some length of text.

The outputs of the threshold-logic matrix 44 may be inputs to the logical-product matrix 46. The logical-product matrix 46 may selectively generate “product” results (e.g., “AND” function in Boolean logic). The logical-product matrix 46 may be implemented as a square matrix, in which the number of output products is equal the number of input lines from the threshold-logic matrix 44, or the logical-product matrix 46 may have a different number of inputs than outputs. The resulting product values may be output to the logical-sum matrix 48.

The logical-sum matrix 48 may selectively generate sums (e.g., “OR” functions in Boolean logic.) The logical-sum matrix 48 may also be a square matrix, or the logical-sum matrix 48 may have a different number of inputs than outputs. Since the inputs are logical products, the outputs of the logical-sum matrix 48 may be logical-Sums-of-Products (e.g., Boolean logic Sum-of-Product (SOP) form). The output of the logical-sum matrix 48 may be received by the initialization-routing matrix 50.

The initialization-routing matrix 50 may reset portions of the detection array 34 and the aggregation module 24 via the aggregation-routing matrix 42. The initialization-routing matrix 50 may also be implemented as a square matrix, or the initialization-routing matrix 50 may have a different number of inputs than outputs. The initialization-routing matrix 50 may respond to signals from the logical-sum matrix 48 and re-initialize other portions of the pattern-recognition processor 14, such as when a search criterion is satisfied or determined to be not further satisfiable.

The aggregation module 24 may include an output buffer 51 that receives the outputs of the threshold-logic matrix 44, the aggregation-routing matrix 42, and the logical-sum matrix 48. The output of the aggregation module 24 may be transmitted from the output buffer 51 to the CPU 20 (FIG. 1) on the output bus 26. As described further below, the output buffer 51 may include or may itself be a results buffer 25. In some embodiments, an output multiplexer may multiplex signals from these components 42, 44, and 48 and output signals indicative of satisfaction of criteria or matches of search terms to the CPU 20 (FIG. 1). In other embodiments, results from the pattern-recognition processor 14 may be reported without transmitting the signals through the output multiplexer, which is not to suggest that any other feature described herein could not also be omitted. For example, signals from the threshold-logic matrix 44, the logical-product matrix 46, the logical-sum matrix 48, or the initialization routing matrix 50 may be transmitted to the CPU in parallel on the output bus 26.

FIG. 3 illustrates a portion of a single feature cell 30 in the search-term array 32 (FIG. 2), a component referred to herein as a search-term cell 54. The search-term cells 54 may include an output conductor 56 and a plurality of memory cells 58. Each of the memory cells 58 may be coupled to both the output conductor 56 and one of the conductors among the plurality of input conductors 37. In response to its input conductor 37 being selected, each of the memory cells 58 may output a value indicative of its stored value, outputting the data through the output conductor 56. In some embodiments, the plurality of input conductors 37 may be referred to as “word lines”, and the output conductor 56 may be referred to as a “data line”.

The memory cells 58 may include any of a variety of types of memory cells. For example, the memory cells 58 may be volatile memory, such as dynamic random access memory (DRAM) cells having a transistor and a capacitor. The source and the drain of the transistor may be connected to a plate of the capacitor and the output conductor 56, respectively, and the gate of the transistor may be connected to one of the input conductors 37. In another example of volatile memory, each of the memory cells 58 may include a static random access memory (SRAM) cell. The SRAM cell may have an output that is selectively coupled to the output conductor 56 by an access transistor controlled by one of the input conductors 37. The memory cells 58 may also include nonvolatile memory, such as phase-change memory (e.g., an ovonic device), flash memory, silicon-oxide-nitride-oxide-silicon (SONOS) memory, magneto-resistive memory, or other types of nonvolatile memory. The memory cells 58 may also include flip-flops, e.g., memory cells made out of logic gates.

FIGS. 4 and 5 depict an example of the search-term cell 54 in operation. FIG. 4 illustrates the search-term cell 54 receiving a term that does not match the cell's search term, and FIG. 5 illustrates a match.

As illustrated by FIG. 4, the search-term cell 54 may be configured to search for one or more terms by storing data in the memory cells 58. The memory cells 58 may each represent a term that the data stream 12 might present, e.g., in FIG. 3, each memory cell 58 represents a single letter or number, starting with the letter “a” and ending with the number “9”. Memory cells 58 representing terms that satisfy the search term may be programmed to store a first value, and memory cells 58 that do not represent terms that satisfy the search term may be programmed to store a different value. In the illustrated example, the search-term cell 54 is configured to search for the letter “b”. The memory cells 58 that represent “b” may store a 1, or logic high, and the memory cells 58 that do not represent “b” may be programmed to store a 0, or logic low.

To compare a term from the data stream 12 with the search term, the row decoder 28 may select the input conductor 37 coupled to memory cells 58 representing the received term. In FIG. 4, the data stream 12 presents a lowercase “e”. This term may be presented by the data stream 12 in the form of an eight-bit ASCII code, and the row decoder 28 may interpret this byte as a row address, outputting a signal on the conductor 60 by energizing it.

In response, the memory cell 58 controlled by the conductor 60 may output a signal indicative of the data that the memory cell 58 stores, and the signal may be conveyed by the output conductor 56. In this case, because the letter “e” is not one of the terms specified by the search-term cell 54, it does not match the search term, and the search-term cell 54 outputs a 0 value, indicating no match was found.

In FIG. 5, the data stream 12 presents a character “b”. Again, the row decoder 28 may interpret this term as an address, and the row decoder 28 may select the conductor 62. In response, the memory cell 58 representing the letter “b” outputs its stored value, which in this case is a 1, indicating a match.

The search-term cells 54 may be configured to search for more than one term at a time. Multiple memory cells 58 may be programmed to store a 1, specifying a search term that matches with more than one term. For instance, the memory cells 58 representing the letters lowercase “a” and uppercase “A” may be programmed to store a 1, and the search-term cell 54 may search for either term. In another example, the search-term cell 54 may be configured to output a match if any character is received. All of the memory cells 58 may be programmed to store a 1, such that the search-term cell 54 may function as a wildcard term in a search criterion.

FIGS. 6-8 depict the recognition module 22 searching according to a multi-term search criterion, e.g., for a word. Specifically, FIG. 6 illustrates the recognition module 22 detecting the first letter of a word, FIG. 7 illustrates detection of the second letter, and FIG. 8 illustrates detection of the last letter.

As illustrated by FIG. 6, the recognition module 22 may be configured to search for the word “big”. Three adjacent feature cells 63, 64, and 66 are illustrated. The feature cell 63 is configured to detect the letter “b”. The feature cell 64 is configured to detect the letter “i”. And the feature cell 66 is configured to both detect the letter “g” and indicate that the search criterion is satisfied.

FIG. 6 also depicts additional details of the detection array 34. The detection array 34 may include a detection cell 68 in each of the feature cells 63, 64, and 66. Each of the detection cells 68 may include a memory cell 70, such as one of the types of memory cells described above (e.g., a flip-flop), that indicates whether the feature cell 63, 64, or 66 is active or inactive. The detection cells 68 may be configured to output a signal to the activation-routing matrix 36 indicating whether the detection cell both is active and has received a signal from its associated search-term cell 54 indicating a match. Inactive features cells 63, 64, and 66 may disregard matches. Each of the detection cells 68 may include an AND gate with inputs from the memory cell 70 and the output conductor 56. The output of the AND gate may be routed to both the detection bus 38 and the activation-routing matrix 36, or one or the other.

The activation-routing matrix 36, in turn, may selectively activate the feature cells 63, 64, and 66 by writing to the memory cells 70 in the detection array 34. The activation-routing matrix 36 may activate feature cells 63, 64, or 66 according to the search criterion and which search term is being searched for next in the data stream 12.

In FIG. 6, the data stream 12 presents the letter “b”. In response, each of the feature cells 63, 64, and 66 may output a signal on their output conductor 56, indicating the value stored in the memory cell 58 connected to the conductor 62, which represents the letter “b”. The detection cells 56 may then each determine whether they have received a signal indicating a match and whether they are active. Because the feature cell 63 is configured to detect the letter “b” and is active, as indicated by its memory cell 70, the detection cell 68 in the feature cell 63 may output a signal to the activation-routing matrix 36 indicating that the first search term of the search criterion has been matched.

As illustrated by FIG. 7, after the first search term is matched, the activation-routing matrix 36 may activate the next feature cell 64 by writing a 1 to its memory cell 70 in its detection cell 68. The activation-routing matrix 36 may also maintain the active state of the feature cell 63, in case the next term satisfies the first search term, e.g., if the sequence of terms “bbig” is received. The first search term of search criteria may be maintained in an active state during a portion or substantially all of the time during which the data stream 12 is searched.

In FIG. 7, the data stream 12 presents the letter “i” to the recognition module 22. In response, each of the feature cells 63, 64, and 66 may output a signal on their output conductor 56, indicating the value stored in the memory cell 58 connected to the conductor 72, which represents the letter “i”. The detection cells 56 may then each determine whether they have received a signal indicating a match and whether they are active. Because the feature cell 64 is configured to detect the letter “i” and is active, as indicated by its memory cell 70, the detection cell 68 in the feature cell 64 may output a signal to the activation-routing matrix 36 indicating that the next search term of its search criterion has been matched.

Next, the activation-routing matrix 36 may activate the feature cell 66, as illustrated by FIG. 8. Before evaluating the next term, the feature cell 64 may be deactivated. The feature cell 64 may be deactivated by its detection cell 68 resetting its memory cell 70 between detection cycles or the activation-routing matrix 36 may deactivate the feature cell 64, for example.

In FIG. 8, the data stream 12 presents the term “g” to the row decoder 28, which selects the conductor 74 representing the term “g”. In response, each of the feature cells 63, 64, and 66 may output a signal on their output conductor 56, indicating the value stored in the memory cell 58 connected to the conductor 74, which represents the letter “g”. The detection cells 56 may then each determine whether they have received a signal indicating a match and whether they are active. Because the feature cell 66 is configured to detect the letter “g” and is active, as indicated by its memory cell 70, the detection cell 68 in the feature cell 66 may output a signal to the activation routing matrix 36 indicating that the last search term of its search criterion has been matched.

The end of a search criterion or a portion of a search criterion may be identified by the activation-routing matrix 36 or the detection cell 68. These components 36 or 68 may include memory indicating whether their feature cell 63, 64, or 66 specifies the last search term of a search criterion or a component of a search criterion. For example, a search criterion may specify all sentences in which the word “cattle” occurs twice, and the recognition module may output a signal indicating each occurrence of “cattle” within a sentence to the aggregation module, which may count the occurrences to determine whether the search criterion is satisfied.

Feature cells 63, 64, or 66 may be activated under several conditions. A feature cell 63, 64, or 66 may be “always active”, meaning that it remains active during all or substantially all of a search. An example of an always active feature cell 63, 64, or 66 is the first feature cell of the search criterion, e.g., feature cell 63.

A feature cell 63, 64, or 66 may be “active when requested”, meaning that the feature cell 63, 64, or 66 is active when some condition precedent is matched, e.g., when the preceding search terms in a search criterion are matched. An example is the feature cell 64, which is active when requested by the feature cell 63 in FIGS. 6-8, and the feature cell 66, which active when requested by the feature cell 64.

A feature cell 63, 64, or 66 may be “self activated”, meaning that once it is activated, it activates itself as long as its search term is matched. For example, a self activated feature cell having a search term that is matched by any numerical digit may remain active through the sequence “123456xy” until the letter “x” is reached. Each time the search term of the self activated feature cell is matched, it may activate the next feature cell in the search criterion. Thus, an always active feature cell may be formed from a self activating feature cell and an active when requested feature cell: the self activating feature cell may be programmed with all of its memory cells 58 storing a 1, and it may repeatedly activate the active when requested feature cell after each term. In some embodiments, each feature cell 63, 64, and 66 may include a memory cell in its detection cell 68 or in the activation-routing matrix 36 that specifies whether the feature cell is always active, thereby forming an always active feature cell from a single feature cell.

FIG. 9 depicts an example of a recognition module 22 configured to search according to a first search criterion 75 and a second search criterion 76 in parallel. In this example, the first search criterion 75 specifies the word “big”, and the second search criterion 76 specifies the word “cab”. A signal indicative of the current term from the data stream 12 may be communicated to feature cells in each search criterion 75 and 76 at generally the same time. Each of the input conductors 37 spans both of the search criteria 75 and 76. As a result, in some embodiments, both of the search criteria 75 and 76 may evaluate the current term generally simultaneously. This is believed to speed the evaluation of search criteria. Other embodiments may include more feature cells configured to evaluate more search criteria in parallel. For example, some embodiments may include more than 100, 500, 1000, 5000, or 10,000 feature cells operating in parallel. These feature cells may evaluate hundreds or thousands of search criteria generally simultaneously.

Search criteria with different numbers of search terms may be formed by allocating more or fewer feature cells to the search criteria. Simple search criteria may consume fewer resources in the form of feature cells than complex search criteria. This is believed to reduce the cost of the pattern-recognition processor 14 (FIG. 2) relative to processors with a large number of generally identical cores, all configured to evaluate complex search criteria.

FIGS. 10-12 depict both an example of a more complex search criterion and features of the activation-routing matrix 36. The activation-routing matrix 36 may include a plurality of activation-routing cells 78, groups of which may be associated with each of the feature cells 63, 64, 66, 80, 82, 84, and 86. For instance, each of the feature cells may include 5, 10, 20, 50, or more activation-routing cells 78. The activation-routing cells 78 may be configured to transmit activation signals to the next search term in a search criterion when a preceding search term is matched. The activation-routing cells 78 may be configured to route activation signals to adjacent feature cells or other activation-routing cells 78 within the same feature cell. The activation-routing cells 78 may include memory that indicates which feature cells correspond to the next search term in a search criterion.

As illustrated by FIGS. 10-12, the recognition module 22 may be configured to search according to complex search criteria than criteria that specify single words. For instance, the recognition module 22 may be configured to search for words beginning with a prefix 88 and ending with one of two suffixes 90 or 92. The illustrated search criterion specifies words beginning with the letters “c” and “l” in sequence and ending with either the sequence of letters “ap” or the sequence of letters “oud”. This is an example of a search criterion specifying multiple target expressions, e.g., the word “clap” or the word “cloud”.

In FIG. 10, the data stream 12 presents the letter “c” to the recognition module 22, and feature cell 63 is both active and detects a match. In response, the activation-routing matrix 36 may activate the next feature cell 64. The activation-routing matrix 36 may also maintain the active state of the feature cell 63, as the feature cell 63 is the first search term in the search criterion.

In FIG. 11, the data stream 12 presents a letter “l”, and the feature cell 64 recognizes a match and is active. In response, the activation-routing matrix 36 may transmit an activation signal both to the first feature cell 66 of the first suffix 90 and to the first feature cell 82 of the second suffix 92. In other examples, more suffixes may be activated, or multiple prefixes may active one or more suffixes.

Next, as illustrated by FIG. 12, the data stream 12 presents the letter “o” to the recognition module 22, and the feature cell 82 of the second suffix 92 detects a match and is active. In response, the activation-routing matrix 36 may activate the next feature cell 84 of the second suffix 92. The search for the first suffix 90 may die out, as the feature cell 66 is allowed to go inactive. The steps illustrated by FIGS. 10-12 may continue through the letters “u” and “d”, or the search may die out until the next time the prefix 88 is matched.

FIG. 13 depicts an example of another pattern-recognition processor 93. The pattern-recognition processor 93 may operate in a substantially similar manner as described above with respect to the pattern-recognition processor 14 of FIG. 2. However, the pattern-recognition processor 93 may further include a threshold output mask 94, a product output mask 96, a sum output mask 98, and an initialization output mask 100, in addition to the common elements with the pattern-recognition processor 14 of FIG. 2.

The threshold output mask 94, the product output mask 96, the sum output mask 98, and the initialization output mask 100 may generally operate to “mask”, i.e. filter, one or more results received as an input. For example, the threshold logic matrix 44 may be set to search for all known occurrences of, for example, security threats in a data stream 12. However, it may be beneficial to filter these results for one or more specific security threats, such as a particular high-risk threat. Accordingly, the threshold output mask 94 may be set to block all security threats found by the threshold logic 44 except for a specified high-risk security threat. If this high-risk security threat is found, notification of the threat may be transmitted from the threshold output mask 94 to the output buffer 51 for retrieval by the CPU. Thus, the threshold output mask 94, the product output mask 96, the sum output mask 98, and the initialization output mask 100 may form mask modules, each of which may filter the output of a respective matrix 44-50 in an effort to segment one or more specified results from the entire result output of the pattern matching matrices 44-50. In some embodiments, the output mask modules 94-100 may apply associated mask registers to the outputs of the pattern matching matrices 44-50 to facilitate such filtering.

Accordingly, the threshold output mask 94 may operate to generate a search result match based on the result of the threshold-logic matrix 44. As described above, the threshold-logic matrix 44 may include a plurality of counters, e.g., 32-bit counters configured to count up or down based on matches signaled by the recognition module. The threshold-logic matrix 44 may count the number of occurrences of a word in some length of text, such as three “A” symbols found in a string of data. Results from the threshold-logic matrix 44 may be passed to the threshold output mask 94, the output buffer 51, and the logical-product matrix 46. The threshold output mask 94 may utilize the threshold results determined by the threshold-logic matrix 44 to perform an additional match search. This additional match search may include “AND-ing” the threshold results determined by the threshold-logic matrix 44 with, for example, a bit location in the threshold output mask 94.

For example, threshold results may be passed to the threshold output mask 94 along, for example, 32 lines, where each line may correspond to a particular result. Each of these lines may also have a corresponding bit location in the threshold output matrix 94 that may be set to either one or zero, depending on whether the result received on the line corresponding to that bit location is to be selected by the threshold output mask 94. Thus, for any bit location in the threshold output mask 94 set to one, any information received along the corresponding result line from the threshold-logic matrix 44 may be transmitted to the output buffer 51 from the threshold output mask 94. Similarly for any bit location in the threshold output matrix 94 register set to zero, any information received along the corresponding line from the threshold-logic matrix 44 may be masked, i.e. filtered, and, thus, prevented from being transmitted from the threshold output matrix 94 to the output buffer 51. In this manner, the threshold output mask 94 may effectively select which threshold-logic matrix 44 results to pass to the output buffer 51 (e.g., those corresponding to an enabled bit location in the threshold output mask 94) and which results of the threshold-logic matrix 44 to ignore (e.g., those corresponding to an enabled bit location in the threshold output mask 94). It should be noted that while the above discussion has been directed to describing a hardware match via the threshold output mask 94, a software match, utilizing a threshold mask program that functionally performs in a manner similar to that described above may be utilized.

The product output mask 96 may operate to generate a search result match based on the result of the logical-product matrix 46. The logical-product matrix 46 may selectively generate “product” results (e.g., “AND” function in Boolean logic) based on two or more threshold-logic matrix 44 results. For instance, the logical-product matrix 46 may search for both three “A's” and the term “cat.” Results from the logical-product matrix 46 may be passed to the product output mask 96, the output buffer 51, and the logical-sum matrix 48. The product output mask 96 may utilize the product results determined by the logical-product matrix 46 to perform an additional match search. This additional match search may include “AND-ing” the results determined by the logical-product matrix 46 with, for example, a bit location in the threshold output mask 94.

For example, product results of the logical-product matrix 46 may be passed to the product output mask 96 along, for example, 32 lines, where each line may correspond to a particular result. Each of these lines may also have a corresponding bit location in the product output mask 96 that may be set to either one or zero, depending on whether the result received on the line corresponding to that bit location is to be selected by the product output mask 96. Thus, for any bit location in the product output mask 96 set to one, any information received along the corresponding result line from the logical-product matrix 46 may be transmitted to the output buffer 51 from the product output mask 96. Similarly for any bit location in the product output mask 96 set to zero, any information received along the corresponding line from the logical-product matrix 46 may be masked, i.e. filtered, and, thus, prevented from being transmitted from the product output mask 96 to the output buffer 51. In this manner, the product output mask 96 may effectively select which logical-product matrix 46 results to pass to the output buffer 51 (e.g., those corresponding to an enabled bit location in the product output mask 96) and which results of the logical-product matrix 46 to ignore (e.g., those corresponding to an enabled bit location in the product output mask 96). It should be noted that while the above discussion has been directed to describing a hardware match via the product output mask 96, a software match, utilizing a threshold mask program that functionally performs in a manner similar to that described above may be utilized.

The sum output mask 98 may operate to generate a search result match based on the result of the logical-sum matrix 48, in a similar manner to that described above with respect to the threshold output mask 94 and the product output mask 96. The logical-sum matrix 48 may selectively generate “sum” results (e.g., “OR” functions in Boolean logic) or may, based on logical product inputs, create logical Sums-of-Products (e.g., Boolean logic Sum-of-Product (SOP) form). For instance, the logical-sum matrix 48 may search for both three “A's” and the term “cat” or for three “N's” and the term “dog.” Results from the logical-sum matrix 48 may be passed to the sum output mask 98, the output buffer 51, and the initialization-routing matrix 50.

Such sum results may be received by the sum output mask 98 along a set of output results lines. Each of these lines may also have a corresponding bit location in the sum output mask 98 that may be set to either one or zero, depending on whether the result received on the line corresponding to that bit location is to be selected by the sum output mask 98. Thus, for any bit location in the sum output mask 98 set to one, any information received along the corresponding result line from the logical-sum matrix 48 may be transmitted to the output buffer 51 from the sum output mask 98. Similarly for any bit location in the sum output mask 98 set to zero, any information received along the corresponding line from the logical-sum matrix 48 may be masked, i.e. filtered, and, thus, prevented from being transmitted from the sum output mask 98 to the output buffer 51. In this manner, the sum output mask 98 may effectively select which logical-sum matrix 48 results to pass to the output buffer 51 (e.g., those corresponding to an enabled bit location in the sum output mask 98) and which results of the logical-sum matrix 48 to ignore (e.g., those corresponding to an enabled bit location in the sum output mask 98). It should be noted that while the above discussion has been directed to describing a hardware match via the sum output mask 98, a software match, utilizing a threshold mask program that functionally performs in a manner similar to that described above may be utilized.

The initialization output mask 100 may operate to generate a result based on initialization results of the initialization-routing matrix 50. The initialization-routing matrix 50 may selectively reset portions of the detection array 34 and/or the aggregation module 24 via the aggregation-routing matrix 42 based on results from the logical-sum matrix 48. The initialization-routing matrix 50 may also re-initialize other portions of the pattern-recognition processor 14, such as when a search criterion is satisfied or determined to be not further satisfiable. These initialization results may be passed to the output buffer 51 and the initialization output mask 100.

The initialization output mask 100 may utilize the initialization results determined by the initialization-routing matrix 50 to perform an additional match search, whereby a secondary conditional reset may be generated. This additional reset may be generated by “AND-ing” the initialization results determined by the initialization-routing matrix 50 with a secondary condition for the reset of, for example, the detection array 34 and/or the aggregation module 24 via the aggregation-routing matrix 42 by the initialization output mask 100. This secondary condition may be one or more activated bit locations in the initialization output mask 100, whereby the bit locations may correspond to one or more result lines from the initialization-routing matrix 50. A given bit location in the initialization output mask 100 may be set to either one or zero, depending on whether the result received on the line corresponding to that bit location is to be selected by the initialization output mask 100, to effectively select which initialization-routing matrix 50 results to pass to the output buffer 51 and which results of the initialization-routing matrix 50 to ignore. Furthermore, the initialization output mask 100 may be implemented via hardware or via software, utilizing, for example, an initialization mask program that functionally performs in a manner similar to the hardware implementation described above.

Accordingly, the output buffer 51 may receive the output of the threshold-logic matrix 44, the logical-product matrix 46, the logical-sum matrix 48, and the initialization-routing matrix 50, as well as the output of the threshold output mask 94, the product output mask 96, the sum output mask 98, and the initialization output mask 100. The output buffer 51, along with the results buffer 25, may operate as a buffer for the outputs prior to their transmission across output bus 26. Furthermore, the writing of these results to the output buffer 51 may be performed concurrently, i.e., in parallel.

FIG. 14 illustrates an example of the results buffer 25 coupled to the pattern-recognition processor 14 or pattern recognition processor 93. As described above with regard to FIGS. 2 and 13, the results buffer 25 may be included in the output buffer 51. The results buffer 25 may include a first-in first-out (FIFO) buffer 102, a buffer-write-control module 104, a buffer-read-control module 106, and a buffer-configuration module 108. The results buffer 25 may be integrally formed as part of the pattern-recognition processor 14 (e.g., on the same body of silicon), or it may be a separate component or part of a separate component. The results buffer 25 may receive results data from the pattern-recognition processor 14 through an upstream results bus 110, and the results buffer 25 may output results data to the CPU 20 (FIG. 1) through a downstream results bus 112. A configuration bus 114 may place the CPU 20 in communication with the buffer-configuration module 108 in the results buffer 25 and a pattern-recognition processor configuration module 116 that may be used to configure the pattern-recognition processor 14.

The FIFO buffer 102 may be configured to store a plurality of records 118. Each record 118 may store results data, e.g., data relating to the satisfaction of a criterion. Each record 118 may correspond with one instance of the satisfaction of one criterion, or data relating to the satisfaction of the criterion may be stored in several records 118, e.g., several adjacent or otherwise sequential records 118.

Each record 118 may include fields for storing results status information 120, housekeeping information 122, and results data 124. Other embodiments may include additional fields or fewer fields. The results status fields 120 may store data that identifies the data stream 12 and distinguishes the data stream 12 from other data streams that the pattern-recognition processor 14 may be receiving.

The housekeeping fields 122 may store data indicative of the status of the pattern-recognition processor 14 when a criterion is satisfied. For example, the housekeeping fields 122 may store data that indicates whether an error condition has occurred. Examples of error conditions include an input data overflow or a FIFO buffer full condition. The FIFO buffer 102 may include more than about 32 records, more than about 64 records, more than about 128 records, more than about 256 records, or more than about 512 records, for example.

The results data 124 may include data such as which criterion was satisfied, the sequence of terms from the data stream 12 that satisfied the criterion, a term count (e.g., a bit count) that points to the portion of the data stream 12 that satisfied the criterion, or a time period during which the portion of the data stream that satisfied the criterion was received. The results data 124 stored in each record 118 may be categorized as a bank. This bank may include a separate register for storage of each of the match result outputs from each of the threshold-logic matrix 44, the logical-product matrix 46, the logical-sum matrix 48, the initialization-routing matrix 50, the threshold output mask 94, the product output mask 96, the sum output mask 98, and/or the initialization output mask 100. Furthermore, the match results outputs may be written into the bank of registers in parallel. In this manner, the results data 124, i.e., match data, for each record 118 may be received and stored into a bank of registers simultaneously, whereby each separate register may individually store a specified result from a particular matrix or mask.

The buffer-write-control module 108 may be configured to control which data from the upstream results bus 110 is written to which record 118 in the FIFO buffer 102. The buffer-write-control module 102 may include a counter that increments or decrements each time a criterion is satisfied or each time results data is written to a new record 118. The buffer-write-control module may also include memory that indicates which record 118 was most recently output to the CPU 20, and the buffer-write-control module 104 may be configured to write data from the upstream results bus 110 to records 118 containing data that has already been conveyed to the CPU 20.

Similarly, the buffer-read-control module 106 may be configured to indicate which record 118 is the oldest record that has not been read from the FIFO buffer 102. For example, the buffer-read-control module 106 may include a counter that increments or decrements each time a record is read from the FIFO buffer 102, and the count of the counter may identify the oldest unread record 118. The buffer-read-control module 106 may be configured to receive a read command signal 126 from the CPU 20 and to respond to the read command by causing the FIFO buffer 102 to output the data stored by the oldest unread record 118.

The results bus 112 may include different conductors from the bus that conveys the data stream 12, such that the data stream 12 may input data at the same time that the downstream results bus 112 is outputting data. In embodiments in which the results buffer 25 is integrally formed with the pattern-recognition processor 14, the pattern-recognition processor 14 may include separate pins for conveying the data stream 12 in and the results out. Accordingly, results data may be output at the same time that the data stream is input.

Alternatively, the results bus 112 may utilize the same conductors, or pins, to receive the data stream 12 and to output results data, in effect, utilizing a shared bus. For example, the shared bus may be multiplexed, or time-sliced, so that the shared bus may be utilized by the same conductors to receive the data stream 12 and to output results data. However, the time that the shared bus is utilized to transmit input data may exceed the time that the shared bus is utilized to transmit output data, thus yielding more input cycles than output cycles. As such, the input cycles may be given a top priority during the multiplexing of the shared bus. The output cycles may subsequently be fit into time slots that are not being utilized as input cycles, as time allows.

In operation, the pattern-recognition processor 14 may search the data stream 12 in the manner described above with reference to FIGS. 2-13, and results from the search may be buffered in the results buffer 25 before being conveyed to the CPU 20. When a criterion is satisfied, data relevant to the satisfaction of the criteria, such as data that indicates which criterion was satisfied, data that indicates which terms in the data stream 12 satisfied the criterion, and data that indicates which data stream is being searched, may be transmitted through the upstream results bus 110 to the results buffer 25.

Upon receipt of this data, the buffer-write-control module 104 may determine whether there are any free records in the FIFO buffer 102, e.g., records 118 that store data that has already been conveyed to the CPU 20 or records 118 that do not store any data. If no free records are available, the buffer-write-control module 104 may signal the pattern-recognition processor 14 to stop searching the data stream and the CPU 20 to pause transmission of the data stream 12 while the CPU 20 works through the records in the FIFO buffer 102 and creates space. The buffer-write-control module 104 may also store data in the housekeeping information fields 122 of the current or subsequent record entries indicating that the pattern-recognition processor 14 entered a results buffer overflow state.

If the buffer-write-control module 104 determines that at least one free record 118 is available, the buffer-write-control module 104 may write the results data from the upstream results data bus 110 to the free record 118. The buffer-write-control module 104 may designate the record 118 as having been written to but not yet having been read from, and the buffer-write-control module 104 may designate the record 118 as being the newest record relative to the other written records.

At substantially the same time, or at other times, the CPU 20 may transmit the read control signal 126 to the buffer-read-control module 106, thereby signaling the buffer-read-control module 106 to output the data in the oldest record 118 that has not yet been read. Thus, the CPU 20 may “poll” the critical status register to determine if, for example, new records 118 are available for transmission to the CPU 20. The polling by the CPU 20 may occur via the CPU 20 determining if one or more status bits, either internal or external to the results buffer 25, has been set. The setting of the one or more status bits may indicate that new pattern match result data is available for retrieval by the CPU 20.

The buffer-read-control module 106 may also determine whether any unread records 118 exist. If no unread records exist, the buffer-read-control module 106 may signal the CPU 20 that there are currently no unread records. If an unread record 118 does exist, the buffer-read-control module 106 may identify the oldest unread record and convey the data stored by the oldest unread record 118 to the CPU 20. This constitutes a “polling” method whereby the CPU 20 “asks” if new results are available.

Another method, “interrupting”, may constitute an active notification method whereby the CPU 20 is notified of a given match. In this method, the buffer-read-control module 106 may actively transmit a notification signal through the downstream results bus 112 to the CPU 20 notifying and/or interrupting the CPU 20, thus making the CPU 20 aware of the availability of one or more available records 118. Interrupt lines (not illustrated, but considered part of the downstream results bus 112) may be utilized to transmit the notification signal to the CPU 20.

In other embodiments, the buffer-read-control module 106 may convey a portion of the data stored by the oldest unread record 118, e.g., which criterion was satisfied, and the CPU 20 may determine whether to request more of the data stored by the record 118, e.g., which terms from the data stream 12 satisfied the criterion. The CPU 20, when finished with the record 118, notifies the buffer-read-control module 106 that the record in no longer needed. The buffer-read-control module 106 may then designate that record as having been read and as being safe to be overwritten by the buffer-write-control module 104.

The results buffer also reduces delays caused by search result processing. When the data stream 12 is satisfying search criteria faster than the CPU 20 can receive or process the search results, the results buffer 25 may store the unprocessed results data while the CPU 20 catches up. The results buffer 25 may smooth the flow of results data to the CPU 20 even when several search criteria are satisfied at about the same time and, as a result, the pattern-recognition processor 14 may continue to search the data stream 12 while the CPU 20 processes the backlog of search results stored by the results buffer 25.

Additionally, the results buffer 25 may output result data to the CPU 20 at the same time that results from a data stream search are input into the results buffer 25. That is, the results buffer 25 may receive results of the data stream search, into “empty” records 118, while transmitting previously received results to the CPU 20, from the “oldest” unread records 118. This may be accomplished through the storing of the received results of the search in “empty” records 118, as controlled by the buffer-write-control module 104, and the reading of the “oldest” records 118, as controlled by the buffer-read-control module 106. This may reduce delays caused by search result processing.

FIG. 15 illustrates a results bank 128 that may correspond to results data 124 for the oldest record 118, for example, the results data 124 for FIFO location 0. The results bank may be a “window” into the FIFO records 118, such that the oldest record 118 is the only record visible to the CPU 20 at any time, readable via the results bank 128. Once the access of the results bank 128 is complete, the CPU 20, for example, may notify the buffer-read-control module 106 that the CPU 20 is finished with the record 118 (i.e., the oldest stored results data 124) of results bank 128. In response, the buffer-read-control module 106 may advance the FIFO queue, making the next record 118, i.e., FIFO location 1, visible as the new oldest record 118 corresponding to the results bank 128. Thus, the CPU 20 may only be able to address the current record 118 corresponding to the results bank 128. The remaining records 118 may remain hidden in the FIFO queue from the CPU 20.

The results bank 128 may include a group of registers 130. This group of registers 130 may be utilized to store the results data 124. For example, the group of registers 130 may include a separate register 132-146 for storage of each of the match result outputs from each of the threshold-logic matrix 44, the logical-product matrix 46, the logical-sum matrix 48, the initialization-routing matrix 50, the threshold output mask 94, the product output mask 96, the sum output mask 98, and the initialization output mask 100. Furthermore, each register 132-146 in the group of registers 130 may be written to in parallel. In this manner, the results data 124 for a record 118 corresponding to a given FIFO location may be received and stored into the group of registers 130 simultaneously, whereby each separate register 132-146 may individually store a specified result from a particular matrix 44-50 or mask 94-100.

While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims. 

1. A system comprising: a pattern-recognition processor comprising: pattern matching matrices adapted to generate first results based at least in part on searches for one or more values in a data stream, and mask modules adapted to generate second results based at least in part on filtering the first results; and a results buffer, wherein the results buffer includes a plurality of first-in-first-out (FIFO) locations adapted to store the first and second results generated by the pattern-recognition processor.
 2. The system of claim 1, wherein the first and second results stored in each of the plurality of FIFO locations are stored in a bank of registers corresponding to each FIFO location.
 3. The system of claim 2, wherein the bank of registers comprises a plurality of registers each adapted to store match result data corresponding to one of the first results or masked result data corresponding to one of the second results.
 4. The system of claim 3, wherein the pattern matching matrices include a threshold-logic matrix configured to register an occurrence of a value in the data stream as a threshold result, and to output the threshold result as a subset of the first results to one register of the plurality of registers.
 5. The system of claim 4, wherein the mask modules include a threshold output mask configured to: receive the threshold result from the threshold-logic matrix; filter the threshold result; and output the filtered threshold result as a subset of the second results to an additional register of the plurality of registers.
 6. The system of claim 3, wherein the pattern matching matrices include a logical-product matrix configured to generate a product result based at least in part on two or more threshold-logic matrix results, and to output the product result as a subset of the first results to one register of the plurality of registers.
 7. The system of claim 6, wherein the mask modules include a product output mask configured to: receive the product result from the logical-product matrix; filter the received product result; and output the filtered product result as a subset of the second results to an additional register of the plurality of registers.
 8. The system of claim 3, wherein the pattern matching matrices include a logical-sum matrix configured to generate a sum result based at least in part on two or more logical-product matrix results, and to output the sum result as a subset of the first results to one register of the plurality of registers.
 9. The system of claim 8, wherein the mask modules include a sum output mask configured to: receive the sum result from the logical-sum matrix; filter the received sum result; and output the filtered match as a subset of the second results to an additional register of the plurality of registers.
 10. The system of claim 3, wherein the pattern matching matrices include an initialization routing matrix configured to register an initialization result when the initialization-routing matrix determines that a search criterion is satisfied, and to output the initialization result as a subset of the first results to one register of the plurality of registers.
 11. The system of claim 10, wherein the mask modules include an initialization output mask configured to: receive the initialization result from the initialization routing matrix; filter the received initialization result; and output the filtered initialization result as a subset of the second results to an additional register of the plurality of registers.
 12. The system of claim 3, wherein each of the plurality of registers may be written to concurrently.
 13. A method comprising: receiving a data stream; searching the data stream via one or more pattern matching matrices of a pattern-recognition processor, the one or more pattern matching matrices adapted to generate first results based at least in part on searches for one or more values in a stream of data; filtering the first results via one or more mask modules to generate second results; storing the first and second results in a buffer comprising one or more FIFO locations comprising a group of registers.
 14. The method of claim 13, wherein filtering the first results via the one or more mask modules comprises ANDing the first results with values stored in mask registers of the one or more mask modules to generate the second results.
 15. The method of claim 13, wherein searching the data stream via the one or more pattern matching matrices includes searching the data stream via one or more of a threshold-logic matrix, a logical-product matrix, a logical-sum matrix, and an initialization-routing matrix.
 16. The method of claim 13, wherein filtering the first results via the one or more mask modules includes filtering the first results via one or more of a threshold output mask, a product output mask, a sum output mask, and an initialization output mask.
 17. The method of claim 13, wherein each register in the group of registers may be written to concurrently.
 18. The method of claim 13, comprising accessing at least one of the one or more FIFO locations upon determining a status bit is activated, wherein the status bit is activated when pattern match data is stored in the group of registers.
 19. The method of claim 13, comprising accessing at least one of the one or more FIFO locations upon receiving an interrupt signal, wherein the interrupt signal indicates pattern match data is stored in the group of registers.
 20. A system comprising: a plurality of registers, wherein the plurality of registers are adapted to store results data generated by matching matrices via searches for one or more values in a stream of data, and masked result data generated by mask modules via filtering the results data.
 21. The system of claim 20, wherein the plurality of registers are grouped into register banks in a first-in-first-out order.
 22. The method of claim 21, comprising a processor adapted to access at least one of the register banks upon determining if a status bit has been activated, wherein the status bit corresponds to results data being written into the plurality of registers in at least one register bank.
 23. The method of claim 21, comprising a processor adapted to receive an interrupt signal and access at least one of the register banks upon receiving the interrupt signal, wherein the interrupt signal corresponds to results data being written into the plurality of registers in at least one register bank. 